I'm partial to the Bartolini 9j's...
I actually just recently took them out of my fretless jazz to try some Jason Lollar single coils, but I plan on putting them back.
I love Jason Lollar singles in my fretted jazz, but I really got used to the barts in this particular fretless bass.
Hey, now I know...
A couple of pickups that intrigue me are the Nordstrand humcancelling j's, and the humcancelling LIndy Fralins.
Good luck, Nino's work looks fantastic!

Well, I have two Sadowsky humbucking jazz pickups in my fretless, and it sounds amazing. It's not as grindy given my use of flats, but is exactly the sound in my head when I thought of how I wanted a fretless bass to sound.

You're right to think about this in a different frame of reference because it's fretless, as this bass sounds completely different from my other Sadowsky (doing a direct jazz pickup to jazz pickup) comparison. Somehow, I guess vibrating along the wood seems to give it a rounder sound.